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References: Vol. 54 Federal Register 33400, 8/14/89
Organization: Case Western Reserve University, Cleveland, OH (USA)
In its test rule for tributyl phosphate, 54 Fed. Reg. 33400,
8/14/89, EPA requires three tiers of mutagenic testing of this
chemical. First-tier testing is detection of gene mutation
in somatic cells in culture, in vitro mammalian cytogenetics test,
an in vivo mammalian bone marrow cytogenetics chromosomal analysis
test. If the results of somatic cells in culture are positive,
then a sex-linked recessive lethal test in fruitflies is required.
Second tier test is a sex-linked recessive lethal assy in fruit flies,
and a rodent dominant lethal test. Third tier is a rodent heritable
translocation test. EPA did not require mouse visible specific
locus.
In its discussion of the tiers, EPA did not distinguish between
cytogenetic, genotoxic and oncogenic purposes of these tests.
What are the purposes of these tests? Why does EPA say in its
discussion that the third tier tests are not "as sensitive." Is
there a good practical reference on the tests that explains
the logic? Can an inexperienced person hope to understand the
reason for the tiers?